CommEvent

Retrieves a numerical event code indicating the most recent communications event or error.

Not Available at Design time. Read Only at RunTime

MSComm32 and SComm32 have "Similar" Behavior. (SComm32 is improved - See below)

Syntax value = object.CommEvent         object Name of the communications control.   value A numeric expression containing the numeric event code being one of the following             1 = comEvSend There are fewer than Sthreshold number of characters in the transmit buffer.     2 = comEvReceive There are more than Rthreshold number of characters in the receive buffer.     3 = comEvCTS Change in Clear To Send line.       4 = comEvDSR Change in Data Set Ready line. This event is only fired when DSR changes from 1 to 0.     5 = comEvCD Change in Carrier Detect line.            6 = comEvRing Ring detected. Some hardware may not support this event.     7 = comEvEOF End Of File character received.             1001 = comEventBreak A Break signal was received.       1002 = comEventFrame The hardware detected a framing error.       1006 = comEventOverrun The hardware could not receive data fast enough and some was lost     1007 = comEvEOF End Of File character received.       1008 = comEventRxOver Receive Buffer Overflow. There is no room in the receive buffer. Some data was lost     1009 = comEventRxParity Parity Error. The hardware detected a parity error.     1010 = comEventTxFull Transmit Buffer Full. The transmit buffer was full while trying to queue a character.     1011 = comEventDCB An error occurred while setting up the Windows Com driver.           Example     If object.CommEvent > 1000 then       MsgBox ("A communications ERROR occurred") End If

Remarks:

When using Event driven communications you would generally respond to the OnComm event and then interrogate the CommEvent property to decide what the cause of the OnComm event was. (The CommEvent property contains the code/reason for the raising of the OnComm event)

If you are not using an OnComm event in your project then you can still interrogate this property to retrieve the most recent event or error status.

Improvement(s)

When using MSComm32 the CommEvent property can, under some conditions, change unexpectedly - for example if MSComm32 attempts to fire another comm event before you finish executing the previous one. (Under some conditions MSComm32 OnComm event is re-entrant)

When you are handling an SComm32 OnComm event no further events will be triggered - any further events are queued so that you get them one after the other - the CommEvent property will therefore not change unexpectedly.